Evaluation of Tension Perpendicular to Grain Strengths in Small Clear Samples of Sugar Maple for Radial,Tangential and 45-Degree Loading Directions

Abstract

The discussion of the importance of the perpendicular tension strength to better understand the wood's mechanical behavior in several situations, such as shrinkage analysis, glued laminated beam failure analysis, has become clear that more basic input information on tension perpendicular to grain is needed. This work investigated tension perpendicular to grain properties in three different orientations, for radial, tangential and 45-degree directions, using Sugar Maple specimens, and testing methodology according to ASTM D143. In addition, the influence of the density on tension strength values for each direction was analyzed. Furthermore, the failure modes of radial, tangential and inclined specimens are shown and a numerical simulation is presented in order to verify the tendency of the ruptures. From the statistical analysis, it can be concluded that the experimental results of tension perpendicular to grain strength loaded in the radial and tangential directions show a significant statistical difference. Strengths obtained at 45-degrees differ significantly from the other directions.

Numerical and Experimental Analysis of Wood Tensile Strength Perpendicular to the Grain

“…Mascia et al (2020) reported f t90 values ranging from 2 MPa to 8 MPa, close to the values obtained from the ABNT NBR 7190 (1997) test method, while Schlotzhauer et al (2019) reported strength values from 7.2 MPa to…”

“…The failure mode observed in the specimens tested according to the Brazilian standard was the separation of the fibers perpendicularly to the longitudinal direction in the cut section (Figure 6a). There was a concentration of stresses in the central region of the specimen, which was responsible for the rupture of the specimen during the test, as seen in Mascia et al (2020).…”

“…Silva JVF, Araujo PLS, Oliveira KA, Silva MFF, Oliveira CA, Molina JC 2 strength values for the same mechanical property considered (Tanaami, 1993;Matos & Molina, 2016;Mascia et al, 2020). Based on the ABNT NBR 7190 (1997) standard, the specimen with standardized dimensions is subject to a single tension effort, and in the ISO 13910 (2005) standard, the specimen is tested in bending, combining tension, compression, and shear, to determine the tensile strength in the direction perpendicular to the grain (see Figure 1).…”

“…Wood is a natural material with variations in strength, elasticity, among other properties, which can occur as a function of the variation in the angle of the fibers, presence of defects, or even as a function of the percentage of moisture present in the wood (Rocha et al, 2018). Wood is also known for its orthotropic characteristics that result in different mechanical properties for the three different orthogonal directions considered (tangential, longitudinal, and radial) (Costa et al, 2020;Mascia et al, 2020).…”

“…The knowledge of the tensile strength perpendicular to the grain is important to evaluate the mechanical performance of wood, especially in situations where these stresses are present, such as in CLT slabs and in some cases of MLC beams (Bidakov & Raspopov, 2018;Wu et al, 2020). However, this thematic area of study still under discussion does not have many papers published (Tanaami, 1993;Schlotzhauer et al, 2019;Mascia et al, 2020).…”